This was a plot bunny for over two months. Then two minutes of watching BBC America turned these bunnies into a story. This definitely isn't the best one, but better are coming, I promise.
Disclaimer: I do not own any of the plots or characters from Doctor Who.
The TARDIS was lonely. For the millionth time, the Doctor considered that maybe it was too big.
That was the problem with always having somebody with him; when they left, he couldn't be alone. Sometimes he might just sit on the floor and shed a year, feeling the regeneration egging at him, waiting for him to finally change.
It was lonely in the TARDIS. And it wasn't as though he could just replace his companions; he had to happen upon them. So it remained lonely, floating out through all space and time. No matter how beautiful the planet or friendly the creatures, it would always be sad.
If only there could be another person by him, it would be cheeky grins and amazed eyes. They would take away his loneliness, make him feel well again. But there was not.
It would just be the Doctor and his memories, which didn't make him feel any better. No matter how hard he tried to cure it, he was plagued. Plagued by being alone.